The present embodiments relate to a device and a method for regulating a radiation dose.
Radiation therapy includes irradiating diseased tissue with X-ray beams, electron beams or particle beams. For example, particle therapy has developed over the last few years into an established method for the treatment of tissue (e.g., tumorous diseases). However, irradiation methods, as deployed, for example, in particle therapy, may also be deployed in non-therapeutic areas such as, for example, the irradiation of phantoms or non-living bodies for the purposes of research work and/or during the irradiation of materials.
During particle therapy, particles are generated (e.g., ions such as protons, carbon ions or other types of ions). The particles are accelerated to high energies in an accelerator, formed into a particle beam and directed at the tissue to be irradiated. The particles penetrate the tissue to be irradiated where the particles discharge energy of the particles in a circumscribed region. The depth of penetration of the particle beam into the tissue to be irradiated is primarily a function of the energy of the particle beam. The greater the energy of the particle beam, the deeper the particles penetrate the tissue to be irradiated.
During the radiation therapy planning process, the total quantity of the radiation to be supplied by the irradiation device is to be defined. This may be expressed by a number of monitor units (MUs) for treatment with external electron or photon light beams or as ion pulse counters that count treatments with protons or heavy ions. The following explanation applies to MUs, but all the explanations below are also applicable to ion pulse counters.
A dose calculation algorithm in treatment planning software is calibrated to calculate one radiation dose per monitor unit D/MU to enable the prescription of an absolute dose that may be used to determine the required MU.
There are different options for determining the desired dose. The different options include, for example: dose at a reference point is X Gy, or the maximum dose is X Gy; or the average dose at a target area or volume is X Gy, or the dose of Y % of the maximum dose of isoline or isosurface is X Gy. If the dose distribution in the target area is not constant, dose coverage of the tumor is to be minimized. This may be the case with electron-beam treatments, with conventional treatments with photon light beams, with treatments with scanned particle light beams, with brachytherapy treatment, or with advanced treatment techniques such as, for example, intensity-modulated radiation therapy and radiosurgery. The renormalization of the dose may entail a repetitive, laborious and long-winded trial and error process when amending the prescribed dose or during the renormalization of the dose, and when observing changes in a specific isoline record.